Objects over curved surface
The simplest way to recreate the mesh:
(in Blender 2.8)

1) Add a cube (Add->Mesh->Cube)
Then select and remove all but two sides (Delete->Faces).  



2) Bevel the only edge that remained using the Bevel Tool.
Shortcut: Ctrl+B
Set the parameters as desired.  



3) Set smooth shading, so it's perfectly smooth.


You're done.
You can now position it as you need.

Tip:
If you're a beginner, switch to 2.8. (or 2.81)
It has waaay more friendly user interface and is much easier to work with.